Resilient curve element of plastics material with longitudinal and transverse struts for a lordosis support with adjustable curvature

ABSTRACT

An elastic contouring assembly for a lumbar support system includes an adjustable contouring element having a central longitudinal strut and an integral shoulder for attachent of an adjustment device. A tensioning cable having one end attached to the contouring element and an opposite end attached to the adjustment adjusts the curvature of the contouring element. Guide elements extend from the central longitudinal strut and include aperatures to receive the tensioning cable. Each of the apertures define an individual clearance height from the central longitudinal strut, and as the clearence heights differ, the radius of the contouring element can be adjusted by extending or retracting the tensioning cable.

The invention concerns an elastic contouring element made of plasticwith longitudinal and transverse struts for a lumbar support systemhaving an adjustable curvature including a tensioning device, one end ofwhich is connected to a contouring element by means of a fasteningelement and the other end of which is connected to a cam device foradjusting the curvature of the contouring element.

Such a contouring element is known from the DE-C1-43 20 105. Thecontouring element known from it requires additional parts with regardto its connection to the adjustment device and a considerable amount ofassembly time.

It is the object of the invention to improve a contouring element forlumbar support in such a manner that it can be simply manufactured in acost-effective way and that it can be assembled at low cost. It is afurther object of the invention to attach a contouring element simplyand quickly to a frame or a part of a frame of a back-rest withouttools.

The first-mentioned object is achieved by a contouring element with thecharacteristics of claim 1. Advantageous embodiments of the inventioncan be seen in the subordinate claims.

Below, the invention is described in more detail on the basis of theexample of an embodiment with reference to drawings. The following isshown:

FIG. 1A top view of a contouring element according to the invention,

FIG. 2 a cross-section through a contouring element according to FIG. 1,

FIG. 3 a tensioning device,

FIG. 4 a sectional view of a round peg with flat portions locatedopposite each other at the center portion and at the exposed ends.

The contouring element 1 consists of a truss-like structure withtransverse struts 2 and longitudinal struts 3. In the example of theembodiment, in addition to a central strut 4 two further longitudinalstruts 3 are arranged on either side of it and parallel to it, whichform a central truss-like structure with the transverse struts 2, whichconnect them to each other, and where the entire structure can be curvedaround a horizontal axis by means of the longitudinal struts 3, 4. Thetransverse struts 2 protrude beyond this central truss-like structure onboth sides and can be arranged at an angle to it in order to assure alateral support. The contouring element 1 consists preferably entirelyof plastic, while, however, support inserts made of any materialdesired, e.g. metal, and/or reinforcing ribs can be used. In order tosave weight and/or to affect the bending properties and the stabilityand stiffness, recesses 5 can be provided. At the lower end of thecontouring element 1 a shoulder 6 has been provided, which has been madean integral part of the contouring element 1.

In the example of the embodiment, the shoulder 6 is a part of a housing7 for receiving and supporting an adjustment device. The adjustmentdevice contains a rotatable disk 8, which can be supported in thehousing 7, and which contains a cam 9, and where the disk 8 is firmlyconnected to or is an integral part of a gear with helical teeth, whichis not shown, which meshes with a worm gear (not shown), which issupported in the housing 7, and where the worm gear is connectednon-rotatably to a hand wheel 11 by way of an extension 10. The wormgear is turned by means of the hand wheel 11, which causes the gear andthus also the disk 8 along with the cam 9 to be rotated.

In the example of an embodiment the housing 7 consists of the shoulder 6and a corresponding locking part 12, whose contour is shown in FIG. 1,partly as a dotted line. The shoulder 6 and the locking part 12 containprotrusions or recesses 13, 13', which are indicated, for example, inFIG. 2, and which function as guide means and/or snap connections forjoining and holding together the shoulder 6 and the locking part 12 toform the closed housing 7, as soon as the disk 8, with the cam 9 and thehelical gear as well as the worm gear with the extension 10 and the handwheel 11 are inserted into the corresponding indentations or recesses inthe shoulder 6 and in the locking part 12. The protrusions andindentations 13' can all be shaped in such a manner that they correspondto the thickness of the shoulder 6 or the locking part 12, so that thefree end of the protrusion can be welded in place, for example byultrasound, at the exit point of the open indentation extended throughit. Shoulder 6 and locking part 12 may also merely contain aligned bores(not shown), which can be firmly joined to each other by means ofsuitable rivet or screw connections.

The locking part 12 can also be made as an integral part of the shoulder6 of the contouring element 1 by way of a thin portion of the material,which will function as a joint. In order to close the housing 7 it willnow merely be necessary to rotate the locking part 12 by 180° and toconnect it firmly to the shoulder 6.

On the back side of the contouring element 1 on the central strut 4,preferably in the region of the transverse struts 2, bridge elements 14have been placed, which have the function of receiving and guiding atensioning device 15. Preferably, the tensioning device 15 is designedto be elastic in bending, similar to a leaf spring, and it can be madeof a metal, but also of a plastic or other materials, which are elasticin bending. In order to be able to manufacture the bridge elements 14 asan integral part of the contouring element 1 by means of a casting or amolding process, the central strut 4 contains apertures 16 in the regionwhere the bridge elements 14 are located.

At the upper end of the contouring element 1 a fastening element 17 forthe tensioning device 15 is placed, which is located on the centralstrut 4 at the extension of the central axis of the bridge elements 14.In the example of the embodiment shown, the fastening element 17consists of a locking protrusion 18 with a glide ramp 19, which isdirected toward the shoulder 6. The tensioning device 15 contains alocking recess 20, the size of which is such that the locking protrusion18 and the glide ramp 19 can be enclosed by it. The tensioning device 15contains at the end, which is located opposite the locking recess 20, alocking bore 21, the diameter of which has been selected in such a waythat it can receive, free from backlash or with little backlash, the cam8 in a manner that allows it to rotate.

Starting at the shoulder 6, the bridge elements 14 have a reducedclearance height in the direction toward the fastening element 17. Onthe central strut 4, adjacent to the bridge elements 14--preferably toall--elevated portions 22 may be provided, which preferably limit theclearance height to the thickness of the tensioning device 15. By theselection of the clearance height and/or the number and the height ofthe elevated portions, the contouring characteristics can be adjusted;for example, a radius of curvature can be chosen, which differs as afunction of height. The radius of curvature can also be varied on thebasis of the distance of the bridging members 14 from each other. Byvarying the distance between the locking opening 20 and the locking bore21 in the tensioning device 15, the pre-tensioning of the contouringelement 1 can be predetermined.

A variant for fastening the tensioning device 15 at the upper end of thecontouring element 1, which is not shown, may look as follows. In thisvariant, the fastening element 17 consists of a transverse slot in thecentral strut 4 and the tensioning cable 15 contains a hook-shaped bentportion at its upper end 23, which is capable of being inserted into thetransverse slot.

When the adjustment device has been placed inside the housing 7 and thehousing is closed, the tensioning device 15 with the locking opening 20is pushed forwardly from the shoulder 6 under the bridge elements 14and, if required, across the raised portion 22. In this process thefront end 23 of the tensioning device 15 gets to the glide ramp 19, andits locking opening 20 is locked in place behind the locking protrusion18, because the end of the tensioning cable 23 is pre-tensioned by theascending slope of the ramp when the locking opening 20 slides acrossthe free end of the locking protrusion 18. Under certain circumstances,while the contouring element 1 experiences a small degree of manualcurvilinear deflection, the locking bore 21 is now positioned above thecam 9. By means of the pre-tensioning of the end of the tensioningdevice 15 with respect to the locking opening 20, which is brought aboutby the clearance height of the adjacent pair of bridging strut 14 andelevated portion 22, it (the locking opening) slides on the cam 9 untilit--allowing a relative rotation between the cam 9 and the tensioningcable 15--is positioned at the bottom of the cam in contact with thedisk 8. Thus, a firm connection between the tensioning device 15 and thecam device has been made without a tool having been required. Theattachment can, however, also be made, for example, by means of a rivetjoint or a snap ring.

In the example of the embodiment a fastening element is provided at thelower end of the housing 7 for positioning the contouring element 1within the support parts 24 (see FIG. 4), which are directly attached tothe frame or indirectly fastened to an additional frame portion of aback-rest. The fastening element is preferably constructed as a roundpeg 25, whose central portion is exposed in the housing 7 and whose endsprotrude from the housing 7 (see FIG. 1). In FIG. 4 a view of an exampleof an embodiment of a round peg 25 is shown in the plane of the viewaccording to FIG. 1. From it one can see that the central portion andthe exposed ends are provided with flat areas 26 in such a manner thatthe flat areas 26 are displaced from the central portion and that, atthe ends, they are offset relative to each other by 180°. The supportparts 24 are made more or less hook-shaped, and there is a clearancedistance between the hook-shaped parts, when they are transported in aplane, which clearance corresponds exactly to the thickness of the roundpeg 25 minus the thickness of the flat areas 26 at one end and at thecentral portion. This clearance can, for example in the case of a roundpeg 25, which has a diameter of 5 mm and contains each of the flatareas, amount to from 1 to 3 mm. Below the hook-shaped parts the supportparts are spaced at a distance from each other that is equal to orsomewhat greater than the diameter of the round peg 25.

Thus, in the position shown in FIG. 4, the round peg 25 and thus thecontouring element 1 can be inserted between the hook-shaped supportparts 24, after which, subsequent to a slight rotation about the axis ofthe round peg 25--by only a few degrees--it can no longer be removedfrom the support due to the now effective diameter of 5 mm. In thismanner an extremely quick and secure mounting of the contouring elementsto the frame or frame part is made possible.

The round peg 25 may not contain any flat areas in other examples ofembodiments, and it may be possible to insert it into appropriatesupport members, for example U-shaped support members with elastic legsor cap.-like holders, which can be elastically rotated for enclosing theends of the round peg (all not shown). Further, the contouring element 1may contain fastening and/or guide elements for attaching it to frameparts without the use of tools, for example, to round rods, and forexample, in the form of clips.

I claim:
 1. An elastic contouring element with longitudinal andtransverse struts for a lumbar support system with an adjustablecurvature and a tensioning device having a first end and an oppositesecond end said first end of which is connected to the contouringelement by a fastening element and an opposite second end of which isconnected to an adjustment device for adjusting the curvature of thecontouring element, characterized in that the contouring elementincludes an integral shoulder, the shoulder being attached to a housingfor receiving and supporting the adjustment device, and a plurality ofbridge elements extending from a central longitudinal strut of thecontouring element to guide the tensioning cable, each of the bridgeelements defining a clearance height between the tensioning device andthe central longitudinal strut.
 2. Contouring element according to claim1, characterized in that the clearance heights of the bridge elementsdecrease as the bridge elements approach the fastening element. 3.Contouring element according to claim 1, characterized in that at leastone bridge element is equipped with an elevated portion on the centrallongitudinal strut, which limits the clearance height for the tensioningcable.
 4. Contouring element according to claim 3, characterized in thatthe clearance height, which is limited by the bridge element and theelevated portion, corresponds to the thickness of the tensioning device.5. Contouring element according to claim 1, characterized in that thefastening element consists of a locking protrusion and a correspondinglocking opening at the contouring element or in the tensioning device.6. Contouring element according to claim 5, characterized in that thelocking protrusion is an integral part of the contouring element andcontains a glide ramp facing the shoulder.
 7. Contouring elementaccording to claim 5, characterized in that the locking protrusion is abent, hook-shaped part of the tensioning device, which can be insertedinto a locking opening provided in the central strut.
 8. Contouringelement according to claim 1, characterized in that the tensioningdevice contains a locking bore for receiving the cam.
 9. Contouringelement according to claim 1, characterized in that the shoulder isadditionally connected to the rotatable locking part of the housing bymeans of a thinner material section, which functions as a joint. 10.Contouring element according to claim 9, characterized in that theshoulder and the locking part of the housing contain mutual guidingmeans in the form of projections and recesses.
 11. Contouring elementaccording to claim 1, characterized in that the contouring elementcontains integral fastening elements for the attachment to frame partsof a seat.
 12. Contouring element according to claim 11, characterizedin that the fastening element consists of a round peg located in thehousing such that a portion of the peg is exposed.
 13. Contouringelement according to claim 12, characterized in that the round peg isexposed at a central portion and at each end, the central portion havinga flats area offset by 180° with respect to a flat area located at eachexposed end.
 14. An elastic contouring assembly for a lumbar supportsystem, comprising:a contouring element having a central portionincluding a longitudinally extending central strut; an adjustmentdevice; a tensioning device having one end attached to said contouringelement and an opposite end attached to said adjustment device to adjustthe curvature of said contouring element; and, guide elements extendingfrom spaced apart intermediate locations on said central strut of saidcontouring element, each of said guide elements having an aperture toreceive said tensioning device.
 15. The assembly of claim 14, whereineach of said apertures define an individual clearance height from saidcontouring elements, said clearance height differing for each of saidguide elements.